"Amazon is the undisputed heavyweight champion of downtown Seattle," says Kip Spencer, president of The Spencer Companies, a Seattle real-estate consulting firm. With two gigantic real estate deals announced over the past year, including plans for downtown Seattle's biggest ever development and the purchase of its South Lake Union headquarters for $1.16 billion (together comprising 5.1 million-square-feet of office space), the virtual giant has cemented its place as "the colossus of Seattle real estate," writes Pryne.

"In the 25 or 30 years I've been around downtown Seattle, I've never seen anything remotely like what Amazon has done to the market," says Dale Sperling, former president and CEO of Seattle's Unico Properties.

"Amazon's breathtaking growth — it has moved into about 2.7 million square feet in South Lake Union and the Denny Triangle since spring 2010 — has spearheaded the downtown office market's recovery from record-high vacancy rates brought on by the recession and Washington Mutual's demise," notes Pryne. "The company's contrarian decision to locate downtown could spur more tech and Internet companies to move in from the suburbs, Downtown Seattle Association President Kate Joncas says."

And the company's oversized impact isn't just limited to the commercial real estate market. "Their arrival has helped ignite the city's biggest apartment-construction boom in at least 20 years," says Pryne. "Owners and developers of apartment buildings, condo towers, hotels and retail space are cashing in on the company's growth as well."

"Amazon uses their urban campus and the in-city lifestyle as an effective recruiting tool," says Dean Jones of brokerage Realogics Sotheby's International Realty, "and that's good for downtown housing."